NEW YORK – Four bystanders were shot and killed in the past 18 months due to gang rivalries in northern Manhattan, authorities said Thursday in announcing the indictments of dozens of people over a series of years of shootings, robberies, gun sales, car accidents and much more.

A shooting injured a woman who was eight months pregnant and sitting in a parked car, police and prosecutors said. Another sent balls into a crowded basketball court, where a spectator was hit in the chest.

These victims survived. But four other passersby, aged 44 to 66, did not.

The violence “had an impact on the entire neighborhood, a climate of fear among ordinary residents,” Manhattan District Attorney Alvin Bragg said at a news conference.

The 30 defendants are accused of various crimes, with some being charged with murder. Some defendants have pleaded not guilty, while others have not yet been brought to trial.

Prosecutors say a 2018 murder sparked a chain of brutal retaliations between three groups, known as 200/8 Block, 6 Block Crew and Own Every Dollar Crew, also nicknamed OED.

Authorities say the groups operate in the Inwood area and nearby Washington Heights, the neighborhood where the Tony Award-winning musical and film “In The Heights” is set.

In text messages and social media posts, members threatened rivals and discussed violent plans, according to the indictment. One defendant told an ally to go out with one of his rivals, smoke weed with him and take him downstairs, adding: “He’s going to come after him.” Make sure he doesn’t have a knife or anything.

In total, the groups are accused of 18 shootings that killed a total of seven people.

The prosecutions “are going to have a huge impact” on the safety of the neighborhood, New York City Deputy Police Chief Brian Gill said at the news conference.